Sighal compahy



Fla

March 5, 1929. w 1,704,183

- TRAIN CONTROL Filed Sept. 20, 1923 a I VENTIOR.

' other, or may be deenergized.

Patented Mar 0,

CHARLEES ES'IVJZCK, OF NEVI YORK, ASSZGNTG GENERAL RA'ILVJAY SI HAL CUMFANY, GIT BGCHESTER, NEW YGRK.

TRAIN GOHTROL.

Application filed September fitf, 1923. Serial No. 663,819.

This invention relates to automatic train control systems, and particularly tothe type of systems which continuous inductive influences are transmitted to suitable carcarried train control apparatus to maintain themin their normal inactive condition.

In certain kind of train control system of the continuous inductive type, a two- 'elenient or polyphase relay is provided on the railway vehicle which may be energized to produce a torquein one d lion the the part tie'flow track cirt y called am )li lied ticular type of system referred oi 'al't-e-rnatinn current in the us cuit ahead or the train (coni'eniex the loop circuit), is detected and and is applied to one or the w the relay; and current flowing the two en a simrails in'multiple (conveniently ca plex circuit), is detected and amplified and appliedto the other winding of the relay.

displacementbetween the two currents is necessary to make the relay operateg and ifthe instantaneous polarity of one of the currents is reversed, the relay will operate in the reverse direction. In otherwords, a certain phase relationbetween the currents'in the two circuits is necessary in order to energize the car-carried relay when it should be energized, and conversely, an improper phase relation veenthese two currents may' cause a false energization of this relay. o a train control system oi this kind, a v riation and changing in the phase relation of T the several currents mentioned is very likely.

This is especially true of the loop circuit current on account of the variable ballast resistance which changes the value and phase relation of the current shuntedby the and detected, amplified and applied to the relay. i e

in applying the principle O'if COlltlllllOllS iudu ive control to;v train control system in which the tracr rails themselves aroused to carry-the s' sling current and where 'nating current is used for propulsion purposes which also returns through the track rails, it is found that under certaiir distribution of the propulsion current between the two track rails this propulsion current may falsely energize the 0&1"C&1'1T16Cl relay, even though the frequency of the propulsion'current is widely different from the frequency of the signaling current. @FQVI- tr ain other one of which is energized by the flow' or simplex circuit current flowing in the two rails in multiple, the cancarried and trackway apparatus being designed so that the simplex current is normally of a much smaller value than is the loop circuit current, and the car-carried relay responsive to simplex circuit current is correspondingly more sensitive than is the other elay. With this proportioning of the two currents flowing in the simpler-r and loop circuits, respectively,'the relay connected to be responsive to loop circuit current could not be picked up by simplex circuit current, even though (due to bad bonding or the like) mostvol the simplex current were flowing in one the rails, for the reason that the simplex currenti considerably smaller than is the lloop circuit current and is not large enough to pick up the loop circuit relay. Also, the relay connected to be responsive to simpl r current could not respond to loop circuit current, because the detecting apparatus for the simplex current is located a considerable distance in the rear .01": the firstfewazrles of the train SCI-hatjtllG loop circuit current is shunted away from this detecting apparatus. As a turther assurance that one of these relays will not be picked up by current intended to operate the other relay, these relays and associated circuits may be tuned to respond to currents of different frequencies, and the loop and simplex circuits may similarly be supplied with'currcnts different frequencies, t

is a further object of the present invention, it is proposed to employ in those systems in which alternating current is used for propulsion purposes, means for tuning the car-carried influence detecting appararatus to readily respond to the signaling current but not readily respond to the pro pulsion current, it being assumed that these two currents are of widely different fre- Ill) quencies. More specifically, it is proposed to provide either a shunting circuit or wave filter, so to speak, which 18 tuned for the propulsion current so that any current of the frequency used for propulsion purposes flowing in the car-carried apparatus may low Without producing any detrimental effects upon the relays by leaking through such a shunting circuit, or to provide a barrier for currents of a frequency close to that ol the propulsion current so that these currents can not readily flow in the receiving apparatus.

As a still further object of the present invention, it is proposed to arrange the trackway apparatus so that an indication nuy be obtained, due to the absence of loop circuit current without actually cutting this current entirely oil of the track circuit, but effectively cutting it off as far as the carcarried influence receiving apparatus is concerned. In the proposed system, one indication may be obtained by having two rela*s cner 'ized. a second indication ma 7 be J7 a obtained by havingthe loop circuit relay only energized, a third indicath i by having the simplex relay only energized because the source of energy feeding a certain track section is connected to the entrance end of the section, so that the current in the track rails does not flow ahead of the train, and a fourth indication by having both of these re lays dcenerg'ized.

Other objects, purposes, and characteristic features ofthe invention will appear as the description thereof progresses.

'and circuits will first be described, after which the car-carried apparatus will be de scribed in detail and the operation of the system will be taken up. Although the train control system embodying this invention may be applied to any type of signaling system, such as manual, semi-automatic or automatic block signal systems, using either alternating current or direct current track circuits, for convenience automatic block signal territory employing alternating current track circuits only has been illustrated.

The reference character 1 designates the usual track rails divided by insulated joints ends of two otherblocks H and J having been shown. Since the trackway devices and circuits of the several blocks are the same, they are given the same reference characters with distinctive exponents. Each of the blocks is divided into two parts by insulz'tting joints 3, the first part of which may conveniently be called the first or rear section and the second part the second or advance section ofthe block, the point D designating the junction of these two sections. The first section of each block is provided with the usual track relay '1, whereas a track relay U is provided near the middle part of the second section of each block.

As the present invention is particularly applicable to roads employing electric propulsion currents the insulating joints 2 and 3 have been shown in one of the track rails only, the other track rail acting as a return for the propulsion current. i

At the entrance to each block is provided the usual type of wayside signal, which may either be a position light, a distinctive aspect color light, or a semaphore signal, and for convenience semaphoresignals Z have been ilh t'ated conventionally without showing their well-known operating mechanism :and the control circuits, it being understood that each of these signals will indicate stop when the block at the entrance to'which they are placed isoccupied, or presents dangerous conditions for some other reason, will indicate caution when the next block in advance occupied, and will indicate clear when both of these blocks are unoccupied as well understood by those skilled in the art of railway signaling.

' A suitable transmission l ne comprising the wires 4 is provided along the trackway in any suitable manner for supplying the usual signaling current, which may be of a commercial frequency, such as cycles, or

The exit end of the first section.

llO

circuit current may be readily traced on the drawings, and includes the usual trackcircuit mpedance 6 and the front contact 7. of the track relay U of the second section of the block, so that the first section of the block.

only if unocculit) The circuit for supplying this energy may cetec axle, as more clear be tracer as followsz beginning at the sec- 1; fter. V ondery Winding of the transformer 8, Wire T pprtretus thus far (le- 9,'front contact 10 of the track relay T seri' Ll Wire 1 once]? the track roll of the second tr'l section, wlre 12, Wmchng' 0 CQS HGCQSSQFY O11- elays T and U and 1 to these circuits 1 .1. 1 I tee L'lF-JCK re ay Y of: t e tre Vlith the I s-tool U, Wire 18, the other real e on :1 i. means for Wire 14, front 601 gr v Wire 1Q tre. k irnc. h two rails pedence 17 hec to the secondary Wind; r in for convenr ncc will he 10 the transformer S. 1e simple): cr'cmt curr Q 4 '1 v u L first section relay 'clcener lnlllt current 1,; only flowthe block I 4 r c l V vlocl: 1h ec vmce (block entr: nee end of this see by current hav- J) is clear ant flows through the following 5 ing the same relative polarity through a circnittbeginning at the secondary winccircnit which may be traced as follows: ofthetrensfcrmerQO wire 2-1, front CO1 30 he at the secondary Winding of the tact 22 Wire 23 to the middle point of the r 1 10 in its lowbalancing resistance 24;, where'the current 1; rail of the eecom chvltles between the two track rails 1 of the A l 12 uhng or section the block I to the znllclle the track relfsy r, hroL 1 the fl rner Wire 9, c

t he balancing re 1 0 er e 19, Contact 111 its endof this section, Wire 2*" heel: er 're 1. 3 track circuit impedance cry nun ling of the transform- "o the secondary wmcu; if the 'hvrously, 1t the block next 111 adtransformer 8. y

it should he noted r. the fecal rrorn the exit end to the en ranc' e first section 0 "e block vccl o'i tl're'shn 318K cirr r t and the cer-cerie-il e meratus respond accordingly. v

docs change the operation 0'" the sig--' E The'se ontlsection of the blocl 3O net-ling s stem because the track relay U video on re do r I is pro h simplex circuit current i a y as Well it the source o1 manner as readily seen from the c nwin 's ne end of the s t on as when by means comprising bal'anc' in}: their nntlpov at 3:117; w cllnq of y the midpoint of this section. .1 he rces pointed out art-this time that under erconnecte 7 thin atmospheric and ball-(1st conc' us, it tree rzner 41% may benecesse y to provide two relays inact 51 of the track stead of the track relay U, that is one near Peru l n) each end of this section'in orclerte cause st clyi 1gthe erro ment of treckvey proper sh ting of at least one relay clne tthe presence or a train in this sectio; Th

r 1, it vill he noted i435 1y hiock deprived L ,5 truck feed is change-Ll from the exit end to" or simg circuit current'when the next the entrance cml ot a section of a block, so block in advance is occupieh bees use the 45 that the t1 urrent may not be defront con'ect 22 of the track reHy t. of the tected by act-inc; or i once readvance block is open, e interrupting; the 1m ceiving elements loo 1 l A front oi the front sin pt 3 circuit of the first section otthe Hire n the C lWllO; 1e v tre n ctren or t. and as more c.

t on of a block hos 1 s trackwey circuit feet. need from the exit enrl 01 this section he entrance end of this section when the :ext in advance becomes occupied, and

hrs the silnn-lex c rrent cut of? at woch in question; and that the second secmy (ALL s 1 V 1 I ext eno so unucurrent will fir the two rtion, and neither loop nor may he (letected near as second section. That is, 111 vingr1 o1l1 left to right in the di- V .nl imeans itentl of tl \r the 'treckwey has so i t entrence'encl to this sec-v n or the arrow through a hloclifwhen toe, the track cncult current Wlll be shunted next block 1n advance 1s occuplecl isdet r Y 7 cl o1 simplezi circuit current in the first tran a115, therefore, the current fiowlng Wnl see 1011, 15. cleprlved of loop clrcnlt current not affect the lnfiuencerecelvlng means" lo- 111 the first part of the second SQCEIOIIOIE the block, and is deprived of both loop and simplex current at the exit end of this second section under these traffic conditions, for reasons heretofore explained.

An alternating propulsion current is supplied by a generatorAC which is connected in any suitable manner between one of the track rails a'nd'a suitable wayside conduct-or such as a trolley wire or third rail, represented in the drawings as the trolley wire 80.

Gar-awrred LZjQPflL7"CLitt-8.F0l' convenience, a railway vehicle has been conventionally shown by the first and last axles 30 and 31, respectively, of an engine and tender unit, or a car of a multiple unit electric train, dependent upon the type of system to which the train control system is applied. The propulsion current is conducted from the trolley wire 80 to the motors and other car apparatus by means of a trolley 81, a showing of the particular car-carried motors and equipment bein omitted to simplify the 4 1n n disclosure. Directly in front 01' the first axle 30 is provided a suitable ii'i'ilueuce detecting or receiving element LE for detecting the flow of alternating current in I one direction through one of the rails, and

in the other direction through the other rail (loop circuit current). This loop circuit 1nfluencerece1vmg element LE comp uses a ;core 32 of suitable magnetic material, preferably laminated, insulated between the lamina and supported a suitable clearing distance above the track rails. This core 32 has depending legs and pole pieces 33, 34: and 35, and. is provided with coils 36 and 37 connected in series so that current flowing in one direction in one rail through the axles of the vehicle and back in the other direction through the other rail will induce electro-motive-forces in the windings 36 and 37 which are cumulative; Similarly, a simplex influence receiving car element SE for detecting current flowing through the two rails in multiple (simple); circuit current) is provided in the rear of the axle 31. This element SE comprises a similar core 38 having depending legs and pole pieces 89 and all), respectively, and is provided with a winding ll. in which electromotive-forces are induced ttluc to currents flowing in the same direction in the two rails in multiple.

The loop circuit current influence detecting clement LE is connected to a loop circuit amplifying device, conventionally designated by a square AL. This an'lplifying device AL is conn cted to a relay L, and is so designed that the currents flowing in the loop circuit ahead of the train are detected and amplified and applied to the relay L to control the same. The amplifying device AL and the relay L are designed to function to operate suitable contacts dependent upon the flow of current in the loop circuit ahead of the train. This may be accomplished by current detected, and construct the relayL to function on direct current. The simplex amplifying device AS and the simplex relay S are preferably constructed similar to the devices AL and L just described, but preferably respond to a current of a smaller value than do the devices AL and L.

As heretofore mentioned, in certain types of railway systems the cars and locomotive are propelled by electric current, either cirect or alternating; and in order to make the train control system immune to thejliow of alternating propulsion current in the trackway, suitable tuning devices are preferably provided so as to permit the signaling cur rent to pass freely which signaling current may be assumed to be of 60 cycles, and will readily cause the relay L or S, as the case may be, to respond; whereas the flow of propulsion current, which may be assumed to be of 25 cycles, will not readily find its a y through the amplifying devices to opcrate the relays L and S. Two such tuning devices M and N have been illustrated in the simplex circuit and the loop circuit, respectively. It should, however, be understood that either of the tuning devices M and N may be used in both of these circuits, if desired. In order to impress a maximum voltage on the amplifying device AS as a result of current flowing in the influence receiving element SE, a condenser 47 is connected in series therewith which is of a size to cause potential resonance, that is, produce a maximum voltage across this condense 4-7, and consequently across the amplifying device AS. 7

The tuning device M is connected in multiple with'the lead wires coming from the simplex element SE. This tuning device M comprises an inductance series with a condenser 16. i?) and condenser 46 are that they resonate at the frequency of the propulsion current, that is, this device is tuned for resonance at the frequency of the propulsion cru'rent so that this device offers low impedance and practically forms a shunt for propulsion current frequent"; do-

This inductance tectcd by the in fluence receiving element SE wher as 1t affords a considerable impedance this current would be shunted away from the condenser 47 in multiple with the amplifyhunt ing device AS to a large extent, this H, however, allowing very little signaling current to pass theret-hrough, the signaling of such capacity llll) 110 45 connected in current preferably flowing through the condenser in multiple with the amplifying de-' and in turn energizes the simplex relay S.

The tuning device N comprises an inductance 48 and a condenser 49 connected in multiple which are proportioned to cause resothe condenser 49 the inductance 48 are connected in multiple, a maximum counterclecjtro-motive-force is established to the flow of current of a frequency corresponding to that of the propulsion current through the condenser 50, which is provided for the same reason as is condenser 47. p The inductance s8 and condenser 49, however are also chosen to permit the flow of sig ling current through the device as freely as possibieor practical. In other words, the tuning device N is constructed to form a high impedance to propulsion current and a much lower impedance to signalingncurrent, so that the propulsion current will be entirely, or at least to a large extent, kept out of the con-.

denser 50 in multiple with the amplifying device AL. In order to impress the highest possible voltage on the amplifying device AL, due to signaling current detected by the influence detecting device LE, the capacity of this condenser 50 is such that the voltage drop across this condenser, due to signaling current, is a maximum.

On the vehicle is provided a suitable governor, speed indicating, orspeed-responsive device G, which tells the speed at which the vehicle is moving along the traclrway. For

convenience, this governor has been shown conventionally as comprising a shaft 53 which driven by the axles of the vehicle in any desired manner, so that its rate of rotation corresponds to. that of the axle of the to which it isconnectcd. On this is provided a collar Sl-having ea s to whicn are connected links 55. This collar pinned to the shaft, shown, and therefore the position of this collar is tiXe-d.

Another collar 56, having a peripheral groove, is slidably supported on the shaft 53, and is irovided with ears to which are pivotally secured links 57, which have their free en is pivotally connected to weights 58, the links being pivotally connected to the same weights. Between the collars 5e and 56 and around the shaft 58 is a compression coil spring 59. The rotation of the shaft can, the weights 58 to separate, due to centrifugal force, thereby causing the collar 56 to be moved downwardly in proportion to the speed of the shaft and consequently the speed of the vehicle. Suitably pivotally supported, as by a pin 60,'is a speed indicating arm 61 which has one end engaging the peripheral groove of the collar 56. The other end of this speed arm 61 is adapted to I contact with one or more of the contact segments 62, 63 and 64, depending on the speed oft-he vehicle.

The train control system, as illustrated in Fig. 1, contemplates the requirement of restriction in the speed of the vehicle, and the operation of a suitable manually operable device in response to a change of traiiic con ditions ahead of the vehicle. In order to en force such a restriction in the speed and such manual operation, a suitable electro-pneumatic device EPV is preferably employed. The device EPV preferably acts directly on the air-brake system of the vehicle and applies the brakes if the heretofore mentioned requirements are not carried out, and its construction depends somewhat upon the particular type of air-brake system employed. The most common type of air-brake system one in which thebrake pipe is normally maintained at a predetermined pressure, and in which the brakes are applied if the brake pipe pressure is reduced for any reason,so that the venting of the brake pipe causes an automatic brake application. This device EPV is, therefore, preferbly constructed so that if its coil energized it is maintained in its inactive or ineffective condition, and so that deenergization of its winding effects venting of the brake pipe which is preferably discontinued when the brake pipe pressure has been reduced to a predetermined extent; and which preferably simultaneously with such venting cuts main reservoir pressure off of the en 'ineers brake valve, so that the engineer is unable to recharge the bralre pipe and thereby prevent the automatic brake application and defeat the purpose for which the train-control system provided.

'lhe manually operable device heretofore mentioned preferably comprises a push button 52 connected in the circuits of the carcarried equipment in a manner so that it can not be maliciously used to prevent the requirement of a reduction in the speed, or the like, and thereby defeat the purpose of m and which if properly operated its the train. to proceed.

The contact strips 64, 63 and 62 are preferably of such length that the train may be restricted to a high, a medium and a low permissive speed, which may be assumed to be 60, and 20 miles per hour, respectivel lVith the apparatus in its normal condition, as shown, the electro-pneumatic device EPV energized by current flowing from one terminal B of a suitable source of energy, preferably a battery, through the contacts G5 and 66 of the relays L and S, respectively in their energized position through the contact strip 6 1, speed indicating arm 61, through the EPV back to the other terminal C of said source. Under this traffic condition, the permissive speed of the vehicle is that enforced by the contact strip 64, which may be considered to be 60 miles per hour. If the simplex relay S is deprived of its energy for any reason, the permissive speed of thc'vehicle is reduced to 40 miles per hour enforced by the medium speed contact 63. The circuit for maintaining the EPV energized under this condition of the apparatus (reiayL energized and relay S deen'ergized) may readily be traced on the drawing.

if new the relay S is again energized and relay L is deenergized for any reason, possibly because there is no loop circuit current flowing ahead of the train, this current either being shunted away from the receiving apparatus by another train ahead or being undetectable because it is fed from the entrance end of a section, causes the low speed limit to be enforced since energy is only supplied to the contact strip 62 under this condition by reason of the circuit which may be readily traced in the drawing and including the contact of the reset push button 52. If new for any reason both the relays L and Sare deenergized, the electro-pneumatic device EPV is deenergized regardless of the speed of the train at the time, because none of the segments 62, 63, 64; are now connected to the terminal B of the source of supply, thus deenergizing the EPV and effecting stopping of the train unless the push button 52 is simultaneously depressed.

In order to inform the engineer of the condition of the car-carried apparatus and the permissive speed at which the vehicle nay move, and also to inform him of traffie conditions ahead, suitable signals are preferably provided. In the particular con- SJILlCiZlOB illustrated, four signal lamps G, Y, \i and B have been shown. The signal lamp Gr, indicating clear, is normally energized through the contacts 67 and 68 of the relays L and S, respectively, the caution lamp Y is energized when the relay L is energized and the relay S is deenergized, thus indicating caution, as readily appears from thedrawings. Vith the relay L deenergized and the relay S energized, the two lamps il and R- are connected in series across the source of energy having terminals 13 and C corresponding to a danger indication; and with both the relays L and S deenergized, the lamp R- alone is energized, thus indicating that absolute stoppage of the train will take place unless the engineer tal'res appropriate action to evidence that he is aware of trafiic conditions ahead, which action consists in depressing the push butten 52.

Operation 0 system illustrated Fig. 1.In order to more clearly understand the system as shown in Fig. 1, let us assume that the block J is occupied and that the relay-T is in its deenergized condition, thus putting the signal Z at stop and the signal Z at caution.

Let us now assume that the train illustrated by axles and 31 is approaching in the block H with the apparatus in its normal condition, as shown, with the clear signal lamp G energized. With the track relay T deenergized, the front contacts 22 and 51 assume their lower position so as to deprive both the first sect-ion and the latter part of the second section of the block I of simpler; current. Also with the track relay (lee: zed, the second section of the block I l as i... track feed transferred from the exit end to the entrance end thereof. The net result the first section of the block I is deprived of simplex circuit current whereas the first part of the second section of the tracirway although not entirely deprived of loop circuit current is deprived of that kind of loop circuit currentwhich effects the carcarried apparatus, because the track feed feeds from the rear of the section toward the front, and therefore can not effect the receiving element LE for reasons as heretofore explained, and the second part of the second section is deprived of both loop and simplex circuit current. 7

As the train now moves into the block I, the simplex relay S is deenergized because it is deprived of simplex cu rent, thereby setting up an intermediate speed limit of miles per hour, made effective by the contact segment 63 of the governor G. The train may, therefore, proceed through the first section of the block at the medium speed limit of 10 miles per hour and as soon as it exceeds this speed limit its brakes will be automatically applied because the indicating arm (31 leaves contact segment 63. If new the train reaches the point D simplex current will again be present, thereby energizing the relay S; but the relay L is now dcenergized, because there is no loop circuit currentflowing in the rails ahead of the train. This causes the speed of the train to be restricted to 20 miles per hour enforced by the short-contact segment 62 of the governor G, thus assuring a reduction in speed to at least 20 miles per hour by the time the train reaches the end of the block I. This assurance is due to the proper selection of the point D, so that a train moving at the rate of 40 mph. atthe point D will have its speed reduced to at least 20 miles per hour when it reaches the balancing resistance 28 if the brakes are automatically applied at the point D.

Let us assume that the train continues to move from left to right in the normal direction of traflic, and moves beyond the balancing resistance 28 in the block I. Since the block J is occupied, neither loop nor simplex circuit current is present to energize the carcarried apparatus, so that the relays L and S are both deenergizc l. lVith the con tacts 65 and 71 oil the rela s L and S in their lower position, "he circuit for applying energy to the contact segment 62 broken so that the device EP is decilergized. This wouldordinarily apply the brakes of the train and bring the train to a stop before it reaches the end of the block I, or the signal Z There is, however. provided a partial auxiliary circuit which eludes the push button contact when in may be to allow completed by the engineer if alert the train to proceed. li the eng nor is alert-,he presses the push button 52 as soon as the relays L and S are both dcenergized and the brakes applied, whereupon an auxiliary energizing circuit 1 the electro-pneuinatic valve EPV is established thro h back contacts and 71 oil the relays L and. S and the push button 52 down, permitting release of the brakes and allo vino" the tra to advance at the minimum speed.

As the train moves by the signal Z into the block J its speed is not further restricted, but is maintained at this low speed limit of 20 miles per hour. This is because the first section oi the trachway in the block J is either entirely deprived of track circuit current (loop circuit current) because the second section is occupied and the relay U (not shown) has cut oil the source of current from the first section, or this first section is deprived of loop circuit because this current is shunted away from the train in question by the wheels and axles of the train in the block J, all in accordance with the position at which the train in advance located in the block J.

In practice, the carcarried apparatus is preferably so COIlSllllCi'QCl that the simplex relay S responds to a rather small flow or current in the two track rails in multiple; whereas the loop circuit relay L responds only to a considerably larger current. his is done in order to prevent the loop circuit relay L from being maintained energised by simplex circuit current flowing in one rail alone. For-instance, if the balancing resistance at the t endof asection were broken at its junction to one of the rails, the simplex circuit currentwould flow through one rail back to the other balancing resistance. Since this current flows through one rail only, it would'be in condition to effect the loop circuit influence receiving element LE, ecause there is no neutralizing or deenergizing current flowing in the other rail. To explain, with the simplex current equally divided between two rails in multiple, the voltage induced in the coil 36, for instance, of the'element LE will be counter-balanced by the voltage induced in the coil 37, these coils being wound in the opposite direction about the core 32 so that if one of these currents only is pre ent an effect is produced the amplifying device AL.

as heretofore explained, the loop circar-carried apparatus isso constructed that it does not respon'l to the simplex curnecessary though the simplex cur? flows through one rail only, the loop circuit apparatus will be immune, so to speak, to simple current. On the other hanc, the iplei; current apparatus is un able to don t loop circuit currentbecause this current flows from one ii. to the other through ahead oi the axle 5 1d therefore does not reach the simple); ele .ni'ent SE.

e iiow oi propulsion cur "ent in the rails, assuming "this to he alternating cur of a different and probably lower frequency, is unaole to anect ihe simplex relay S in the particular embodiment illustrated brcz use the tuning device M shunts the amp AS, so to speak, by pr v I t... ice or current resonated shunt in multiple therewith; whereas un balanced prooulsion current which would have the eilect of current flowing in one rail invention, thereifore,.does not depend for its indication on the phase relation of different curr nts in the rails of the trackway, but de pends on two dii'l'erent currents which are segregated, so to speak, by the car axles, and

by reason oi? the fact that one is too small to cause response oi the relay designed to be operated by the other. ln other words, the simplex circuit curixnt can not affect the loop circuit clement her-a it is too small in value, and the loop circuit curred can not allect the simplex circuit element because the first l e-w axles of the train do not allow this loop circuit current to reach the simplex elernent.

Modification using two dz'fl'eren frequencies.ln the system of train control just de scribed, the same frequency was employed for supply ng the various simplex circuits as well e various track or loop circuits. Under certain adverse conditions, it may be difficult to be able to control the two relays L and S independently by their respective tracliway currents, and in such cases it may. be desirable to provide suitable more distinctive currents so that the currentintendill) ed for one will not operate the other of these devices.

In Fig. 2 has been illustrated a tlil'GG-Wll' transmission line including the wires 4, sup-- plying current to the various track or loop circuit transformers heretofore described The various transformers shown correspond to and are used for the same purpose as those heretofore described and have been shown in Fig. 1, the car-carried apparatus should be designed to operate properly on the particular frequencies transmitted to its corresponding trackway apparatus. That is, the simplex circuit apparatus carried on the train must be properly tuned i respond to the frequency of the current supplied by the simplex transformers 20", 29 and il-4: whereas the loop circuit apparatus must be designed for the particular frequency used for the track or loop circuit current supplied by the transformers and In order to simplify the illustration, the three-wire two-frequency transmission line and the associated transformers only have been illustrated. apparatus and the car-carried apparatus are omitted because they are the same as far as he conventional appearance of these devices is concerned, these car-carried devices, however, being tuned for the particular frequencies with which they are to be used.

Having thus shown and described several specific embodiments of the invention, it is desired to be understood that the specific disclosures have been made for illustrative purposes oi'lly, rather than with the view of showing the specific construction preferably employed in practice, and that various modifications, changes and deviations may be made to adapt the invention to any one of the various types of railway systems encountered in practice without departing from the scope or the idea of means underlying the pr sent invention.

\Vhat is desired to be secured by Letters Patent of the United States, is

1. In an automatic train control system for railroads employing alternating current for propulsion purposes, the combination of a trackway divided into blocks by insulating joints, means for causing the How of signaling currents in the rails of said blocks in accordance with traffic conditions ahead, said signaling currents being of a different and distinctive frequency from that of said propulsion current, and car-carried appa- The rest of the traclcway ratus comprising an influencereceiving coil in inductive relation with the track rails, an amplifying device, a circuit including said coil connecting said coil and said amplifying' device, and filtering means connected in series withsaid circuit, said filter ing means including an inductance and a capacity having elect 'ical constants for effecting substantially an infinite impedance to the flow of current having the same frequency as the propulsion curr nt whereas said filtering means only slightly resists the flow of current of a frequency like that of the signaling g' currents.

2. In an automatic train control system of the continuous inductive type; the combination with ear-carried apparatus comprising, one influence receiving means responsive to alternating current of one frequency and consisting of a receiving coil disposed inductively with respect to a track rail on which the train is adapted to move,

an alternating current relay, and an amplifying evice coupled between said receiving coil and said relay, said one influence receiving means including filtering means functioning to render said one receiving means responsive only to current of said one frequency flowing in the track rail; another influence. receiving means responsive to alternating current of a different frequency and consisting of another receiving coil also disposed inductively with respect to a track rail on which the train is moving, another alternating current relay, and another amplifying device coupled between said anotherreceiver and said another relay, said another influence receiving means including filtering means functioning to render said another receiving means responsive only to current of said another frequency; and of tracliway means for supplying alternating currents of both of said frequencies under favorable tratlic conditions ahead train, sliip iilyino only alternating current one of said frequencies if less favorable traflic conditions exist ahead and supplying,

neither of said alternating currents under dangerous trafiic conditions ahead.

3.Car-carr1ed apparatus for automatic train control systems of the continuous inof the llt) sive devices maintained energized by two distinct traclrway circuits through an intervening air gap, the movement of train differently if the two devices are one g zed, if one of these devices only is enei zed, if the other device only is energized, and if both of these devices are deenergized, respectively.

5. In an automatic train control system of the continuous inductive type for railways having their tracks divided into blocks, the combination of means partly on the vehicle and partly along the trackway and acting through an intervening air gap for maintaining a. suitable single phase electro-responsive device on the vehicle energized in response to current flowing down one rail and back through the other in a track circuit, means for controlling the speed of the vehicle and for causing an automatic application'of the brakes if the speed of the vehicle is excessive in accordance with the condition of said electro-responsive device, said track circuit having its energy supplied to the exit end and entrance end when the block in advance is unoccupied or occupied, respectively.

6. In an automatic train control system of the continuous inductive type for railways having their tracks divided into blocks, the combination of means partly on the vehicle and partly along the traclrway and acting through an intervening air gap for maintaining a suitable single phase electro-responsive device on the vehicle energized in response to current flowing down one rail and back through the other in a track circuit, means for controlling the train in accordance with the condition of said electroresponsive device, said track circuit having its energy supplied to the exit and entrance end when the block in advance is unoccupied and occupied, respectively.

7. Car-carried apparatus for automatic train control systems comprising, electroresponsive means on the vehicle controlled from the track in accordance with tra'liic conditions ahead, a brake control device, a speed responsive device driven by an axle of the vehicle, means for actuating said brake control device if the speed of the train is excessive or actuating said device regardless of the speed of the vehicle (absolute stop) in accordance with the condition of said electro-responsive means, and manually operable means operable while the vehicle in motion having an active and an inactive position which if moved to the active position and held there allows the train to proceed regardless of the absolute stop restriction imposed, said manually operable means restricting the movement of the train if it is operated when the absolute stop restriction not enforced, whereby the engineer will not attempt to permanently lock this 1 means for restricting Y manually operable means in its active position.

8. Influence communicating means for automatic train control systems of the continuous inductive type for railway systems using alternating current for propulsion purposes comprising, an influence receiving element mounted on a railway vehicle in inductive relation with a track circuit having signaling current flowing therein, an electroresponsive device operatively connected to said influence receiving element and adapted to be permanently energized in response to current flowing in the trackway circuit, and means connected in acircuit connecting said electro-responsive device and said influence receiving element including an inductance and a condenser which have their electrical constants proportioned so as to tune the circuit to potential resonance for the frequency of the propulsion current but to materially restrict the flow of current having a frequency like that of the signaling current.

9. Car-carried apparatus for automatic train control systems of the continuous inductive type for railway systems using alternating current for propulsion purposes comprising, an alternating current electroresponsive device on the vehicle, an amplifying device connected to said electro-responsive device, a coil in inductive relation with a trackway circuit carrying signaling current for causing the flow of current in a condenser in multiple with the input circuit of said amplifying device, and means connected in series with said coil and with the unit comprising the amplifying device and the condenser in multiple therewith, which serves as a barrier to the flow of current of the frequency of the propulsion current but which readily permits the flow of current of a frequency like that of the signaling current.

10. In an automatic train control system for railroads employing alternating current for propulsion purposes, the combination of a. trackway divided into blocks by insulating joints, means for causing the flow of signaling currents in the rails of said blocks in accordance with traffic conditions ahead, said signaling currents being of a different and distinctive frequency from that of said propulsion current, and car-carried apparatus comprising an influence receiving coil in inductive relation with the track rails, an amplifying device, a circuit including said coil connecting said coil and said amplifying device, and filtering means connected in series with said circuit, said filtering means including an inductance and a condenser connected in multiple and having constants so as to be resonated to the frequency of said propulsion current, whereby said filtering means greatly restricts the flow of propulsion current but only slightly restricts the flow of current of the frequency of the signaling currents.

11. In an automatic train control system for railroads employing alternating current for propulsion purposes, the combination of a traclrway divided into blocks by in sulating joints, means for causing the flow of signaling currents in the rails of said blocks in accordance with trafiic conditions ahead, said signaling currents being of a different and distinctive frequency from that of said propulsion current, and car-carried apparatus comprising an influence receiving coil in inductive relation with the track rails, an amplifying device, a circuit connecting said coil and said amplifying device, and filtering means connected in multiple with said influence receiving coil and said amplifying device, said filtering means including an inductance and a condenser connected in series and having constants so as to be resonated to the frequency of the propulsion current, whereby said amplifying device and said receiving coil are substantially shunted as far as the delivery of alternating current of the i'r'requency of the propulsion current from said receiving coil to said amplifying device is concerned.

12. In an automatic train control system of the continuous inductive type; the combination with car-carried apparatus comprising, one influence receiving means responsive to alternating current of one fre-' quency and consisting of a receiving coil disposed inductively with respect to a track rail on which the train is adapted to move,

an alternating current relay, and an amplifying device coupled between said receiving coil and said relay, said one influence receiving means including filtering means functioning to render said one receiving means responsive only to current of said one frequencyflowing 111 the track rail; another influence receiving means responsive to alternating current of a different frequency.

and consisting of another receiving coil also disposed inductively with respect to a track rail on which the train is moving, another alternating current relay, and another amplifying device coupled. between said another receiver and said another relay, said an other influence receiving means including filtering means functioning to render said another receiving means responsive only to current of said another frequency; and of trackway means for supplying alternating currents of both of said frequencies under favorable traflic conditions ahead of the train, and supplying only alternating current of one of said frequencies if less favorable traflic conditions exist ahead.

l3. Car-carried ammratus for automatic train control systems, comprising a normally energized brake control device, speed control means for (lo-energizing said brake control device if the imposed speed restriction of said speed control means is violated, influence communicating means for imposing speed restrictions by said speed control means depeinling on trafiic conditions ahead, and a manually operable device for preventing an automatic brake application which must assume one position continuously so long as certain traffic conditions exist ahead and must assume another position continuously so long as other trafiic conditions exist ahead to avoid such brake application, whereby said manually operable device is protected against misuse.

In testimony whereof I hereby aflix my signature.

CHARLES F. ESTVVICK. 

